1. Field of the Invention
The present invention relates to heat dissipation in electronic component packages, and more particularly, concerns an improved arrangement for detachably connecting a heat sink to an electronic component package.
2. Description of Related Art
As semi-conductor chip packages, including multi-chip modules and other electronic component packages, become more complex and operate at higher frequencies they generate more heat. The heat has to be removed from the device if it is to continue to operate and also to prolong the life of the device. Thus, in general, the component package configuration and construction is specifically designed to allow for maximized heat dissipation. Heat spreaders and heat sinks are employed in such electronic component packages to transfer heat to a moving air stream or on to another surface.
In the past, adhesives have been employed to attach a heat sink to an electronic component, directly or indirectly. The adhesive is dispensed on the component and the heat sink is accurately positioned in contact with the adhesive. The assembly is then heated in an oven to cure the adhesive. After such curing, the assembly reaches its full mechanical strength, but the heat sink is permanently bonded and can no longer be removed without damage to both heat sink and package. Use of adhesives has a number of other disadvantages. Although readily available, adhesives require additional process steps such as storing, mixing, dispensing and accuracy of placement and curing of adhesive materials. Adhesive must be stored under well controlled temperature or in some cases a two-part adhesive has to be mixed in proper amount which then has a limited shelf life. Dispensing of the adhesive is always difficult since it requires precision consistency of adhesive viscosity which can vary from batch to batch and is affected by temperature variation. Dispensing is a messy step since the dispensing nozzle or head must be cleaned after each process run.
After placement of the heat sink and adhesive onto the component package, the adhesive must be cured under specific temperature and time. This increases process cycle time.
A further problem with use of adhesive is that strength of the adhesive is critically dependent upon clean surfaces to which it must adhere. This requires that the heat sink and the component surfaces must be maintained free of contamination or must be cleaned prior to the dispensing of the adhesive and attachment of the heat sink.
All of these steps increase manufacturing cycle time and the overall cost of the units.
Accordingly, it is an object of the present invention to provide for attachment of a heat sink in a manner that avoids or minimizes above-mentioned problems.